Automatic changeover valve

ABSTRACT

Valve for automatically changing from a depleted gas cylinder to a full-pressure gas cylinder comprising a piston moving in a bore past a discharge outlet, valves having floating mountings on said piston with oppositely extending stems alternately engaging separate supply inlets and O-ring relief valves for venting respective ends of the bore when the corresponding inlet is closed by the piston.

United States Patent 72] Inventors Wayne W. Hay;

Charles S. Thompson, both of Madison, Wis. [21] Appl. No. 848,291 [22]Filed Aug. 7, 1969 [45] Patented Jan. 11, 1972 [73] Assignee AirReduction Company, Incorporated New York, N.Y.

[54] AUTOMATIC CHANGEOVER VALVE 4 Claims, 5 Drawing Figs.

[52] US. Cl 137/113, 25l/D1G. 1 [51] Int. Cl GOSd 11/00 [50] Field ofSearch 137/112, 113, 525, 514.5; 251/205; 91/394, 396

[56] References Cited UNITED STATES PATENTS 3,238,850 3/1966Desmarchelier 91/394 Primary Examiner-Herbert F. Ross AssistantExaminer-David J. Zobkiw Al!0rneys Larry R. Cassett, Edmund W. Bopp andH. Hume Mathews ABSTRACT: Valve for automatically changing from adepleted gas cylinder to a full-pressure gas cylinder comprising apiston moving in a bore past a discharge outlet, valves having floatingmountings on said piston with oppositely extending stems alternatelyengaging separate supply inlets and O-ring relief valves for ventingrespective ends of the bore when the corresponding inlet is closed bythe piston.

mcmenma mm 3163350 FIG. 4 FIG.5

INVENTORS CHARLES S. TXOMPSON ATTORNEY AUTOMATIC CHANGEOVER VALVE Fluidssuch as compressed gases are often supplied in separate containers orcylinders. It is common practice to place one cylinder or bank ofcylinders in service and maintain another full cylinder or bank ofcylinders in reserve. Both are connected to the load and suitable valvesprovided to allow them to be discharged in sequence; i.e., putting thereserve full cylinder in service when the other has been depleted. Thiscan be done manually by operating valves, but it is desirable to providea changeover responsive to pressure loss in the depleted cylinder toturn off the depleted supply and turn on the full pressure fluid supply.

According to the present invention, the valve comprises a casing havinga bore with a discharge outlet, separate highpressure gas inletslaterally spaced from said outlet, a piston laterally movable in saidbore past said outlet and alternately closing one of said high-pressuregas inlets, and means venting the respective ends of said bore when saidcorresponding highpressure inlet is closed by said piston.

Preferably the piston has oppositely extending pins insertable withinthe respective inlets to seal off the same, and the pins are floatingmembers movably retained in the faces of the piston to accommodate minormisalignment.

Preferably said venting means comprise a passage forming a bypass aroundsaid closed high-pressure inlet and connecting the trapped portion ofthe bore with the upstream side of the closed inlet, and an O-ringsealing device which alternately opens and closes the bypass.

Preferably the high-pressure gas inlets are nozzles in the opposite endsof said bore, the bore has grooves on each side of the discharge outletreceiving O-rings for sealing the piston, and said nozzles have O-ringsreceiving and sealing said pins when inserted.

FIG. 1 is a longitudinal section through a valve according to thepreferred embodiment of the present invention, showing the piston on theleft side and the flow being from the right;

FIG. 2 is a similar view showing the piston in transit from oneoperating position to the other;

FIG. 3 is a similar view showing the piston moved to seal off the rightside inlet;

FIG. 4 is an enlarged detail view showing the right bypass relief valveO-ring being lifted as the piston nears the righthand end; and

FIG. 5 is a similar view showing the same O-ring returned as the pistoncomes to rest at the right hand side.

The preferred embodiment of the present invention comprises a casinghaving a bore 12 with a piston 14 slidable therein, a first inlet nozzle16 screwed into one end of the bore 12 and sealed by an outer peripheralO-ring 18 and an inner peripheral O-ring l9, and a second inlet nozzle20 screwed into the other end of the bore 12 and sealed by an outerperipheral O-ring 22 and inner peripheral O-ring 23. The casing 10 isprovided with a lateral delivery port 24, and grooves on each sidethereof for O-rings 26.

The piston 14 is slidable in the bore 12 between the nozzles 16 and 20,and has recesses in each end thereof receiving valve heads 20 and 32retained by snap rings 34 for floating action. The valve head has a stem38 adapted to enter the first inlet nozzle 16 and be sealed therein byan internal O-ring 40. The valve head 32 has a stem 42 adapted to enterthe second inlet nozzle 20 and be sealed therein by an internal 0- ring44.

FIG. I shows the piston 14 on the left side closing the first inletnozzle 16 and permitting fluid to flow from the right inlet nozzle 20 tothe delivery port 24. If both cylinders are at full pressure this pistonposition is accomplished by opening the cylinder valve for the cylinderconnected to the right inlet nozzle 20 before that on the left. However,if the valve for the cylinder attached to the nozzle 18 were openedfirst, the piston would move to the right, and the flow would be justthe reverse of the following discussion. With the piston in thislefthand position the valve for the cylinder connected to the nozzle 16can be opened without causing the piston to move. In

this position the forces acting on the respective ends of the piston 14are different. As shown in FIG. 1, the inlet pressure from nozzle 16 isacting on the exposed area of the valve stem 38 which, for example, maybe a quarter of an inch diameter, and the inlet pressure from nozzle 20is acting on the full piston area having a diameter of, for example,three quarters of an inch. When the in-use pressure from the nozzle 20drops to the point where the force acting to keep the piston to the lefttoward the nozzle is less than the force due to the full cylinderpressure acting on the small diameter valve stem 38, the piston 14starts to move to the right.

As the movement continues to the point where the valve stem 38 breaksits seal on the O-ring 40, full pressure is then applied to the fullpiston area from the left. The difference in the supply pressures nowacting on equal areas causes the piston to move over to the right towardthe nozzle 20.

FIGS. 2 and 3 show the sequence of this motion. FIG. 2 shows the piston14 making a seal on the O-ring 26. FIG. 3 shows the valve stem 42 makinga seal on O-ring 44. Now at this point there is a volume of gas trappedbetween O-rings 25, 44, and 23, and if no relief valve arrangement wereprovided and the piston continued movement, the compression of thetrapped gas would be increased, and be acting on the piston diameter.Then when the pressure on the full-cylinder side dropped to thispressure plus the pressure in the right cylinder, switchover to theright cylinder would occur. This might be of the order of twice theinitial switchover pressure, thereby causing a premature switchoverbefore the left cylinder is fully exhausted.

To compensate for this, O-ring type relief valves 46 and 48 have beenprovided, in respective bypasses around the stem O-ring 44 and 40. Theserelief valves are respectively one way in their action.

These relief O-rings are received in triangular or V-notch grooves inthe nozzle blocks, and the bypasses each comprise an entrance passage 50and an exit passage 52. The entrance passage 50 leads from the insideportion of the nozzle bore ahead of its O-ring 44, to the bottom of therelief O-ring groove. The exit passage 52 leads from a point above thebottom of the groove beyond the top of the O-ring, to the nozzle borebeyond the O-ring 44.

Referring to FIGS. 4 and 5, and with the piston 14 moving to the right,as the pressure between O-rings 26 and 44 builds up through the bypassentrance passage 50, it lifts O-ring 46 (FIG. 4) and allows theincreased pressure to bleed back to the low pressure cylinder. When afull cylinder is connected to the right side, the high pressure in theexit passage 52 tends to squeeze the O-ring relief valve 46 into itsgroove (FIG. 5), sealing off the entrance passage 50 and preventinghigh-pressure gas from acting on the full-piston area. In this way, anynumber of switchover cycles can take place and maintain a relativelyconstant switchover pressure.

The three-piece piston assembly allows the sealing valve stem on eachend to float, to compensate for any misalignment of the nozzle bores andthe bore for the piston 14.

Having thus described our invention what we claim as new and desire toacquire by Letters Patent of the United States is as follows.

We claim:

1. An automatic switchover valve for changing from a depleted to a fullpressure supply, comprising a casing having a bore, said bore having adischarge outlet,

separate high-pressure fluid inlets laterally disposed with respect tosaid discharge outlet, a piston laterally movable in said bore past saidoutlet and alternately closing one of said high-pressure fluid inlet,

seal means adapted to seal the periphery of said piston within said borewhereby fluid is prevented from leaking along the periphery of saidpiston,

said piston having oppositely extending pins insertable within therespective high-pressure inlets to seal off the respective inlets, and

wherein said seal means comprises at least one Oring surrounding theperiphery of said piston.

3. An automatic switchover valve as defined in claim 1 wherein said sealmeans comprises a pair of O-rings.

4. An automatic switchover valve as defined in claim 1 wherein said borehas at least two grooves oppositely spaced with respect to saiddischarge outlet, and said seal means comprises an O-ring disposedwithin each of said grooves.

t: I I

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,633,606 Dated January 11, 1972 lnventoi-(s) W. W. Hay and C. S.Thompson It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 59, "20" should read 3O Col. 2, line 21, "25" should read26 line 69, "inlet" should read inlets Signed and sealed this 15th dayof August 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GO'I'TSCHALK Attesting Officer Commissionerof Patents :ORM USCOMM-DC scam-ps9 .5. GOVERNMENT PRINTING OFFICE 1 I969O36"33

1. An automatic switchover valve for changing from a depleted to a fullpressure supply, comprising a casing having a bore, said bore having adischarge outlet, separate high-pressure fluid inlets laterally disposedwith respect to said discharge outlet, a piston laterally movable insaid bore past said outlet and alternately closing one of saidhigh-pressure fluid inlet, seal means adapted to seal the periphery ofsaid piston within said bore whereby fluid is prevented from leakingalong the periphery of said piston, said piston having oppositelyextending pins insertable within the respective high-pressure inlets toseal off the respective inlets, and means venting the respective ends ofsaid bore to each corresponding high-pressure inlet when saidcorresponding high pressure inlet is closed by said piston, each ventingmeans comprising a passage communicating with the respectivehigh-pressure inlet to allow fluid to be released from within said boreand an O-ring blocking said passage, said O-ring being responsive to anincrease in pressure within said bore to displace said O-ring wherebyfluid is allowed to flow past said O-ring.
 2. An automatic switchovervalve as defined in claim 1 wherein said seal means comprises at leastone O-ring surrounding the periphery of said piston.
 3. An automaticswitchover valve as defined in claim 1 wherein said seal means comprisesa pair of O-rings.
 4. An automatic switchover valve as defined in claim1 wherein said bore has at least two grooves oppositely spaced withrespect to said discharge outlet, and said seal means comprises anO-ring disposed within each of said grooves.